Method and device for separating pasty materials

ABSTRACT

A pasty molding material is divided by a process wherein, for the division, the pasty molding material is brought into contact with at least on stream containing at least one fluid medium.

This application is a 371 of PCT/EP04/01004, filed Feb. 4, 2004.

The present invention relates to a process for the division of pastymolding materials. The division of these materials is effected bybringing the molding materials into contact with a stream which containsat least one fluid medium.

In industrial processes, process steps in which pasty materials have tobe divided frequently occur. Such processes are used, for example, inmass production of plastics products, pharmaceutical products, cleaningagents and personal hygiene compositions, foods, animal feeds orcatalysts, in which pasty materials are molded.

Examples are, inter alia, extrusion processes in which pasty materialsare processed in an extrusion apparatus and are brought into a formrequired by process engineering or for use. Usually, a die whosegeometry determines the diameter and the cross-sectional shape of themolding leaving the extrusion apparatus is mounted at the exit of theextrusion apparatus. In this way, for example, extrudates or hollowextrudates having a wide range of diameters, cross-sectional shapes andgeometries are obtained.

For dividing the pasty materials and hence for establishing the lengthof the moldings, the extrusion apparatuses are equipped withface-cutting apparatuses which cut to length a continuous moldingemerging from the extrusion apparatus. As a rule, this cutting to lengthis effected by means of face-cutting or cutting tools, these toolsgenerally being produced from metal, ceramic, plastic or correspondingcomposition materials.

A considerable disadvantage of these conventional methods for cutting tolength is that the tools are subject to natural wear as a result of thedivision of the pasty molding materials. Repairs and replacement of thetools and frequent downtimes are the consequence.

Further disadvantages occur in particular in the case of moldingmaterials of high viscosity or very inhomogeneous consistency. Depositsof parts of the molding materials on the tools, which inevitably occurduring the division process, result, on the one hand, in losses ofproduct. On the other hand, these deposits also necessitate the cleaningof the tools, which may be frequent under certain circumstances.

In the case of relatively soft molding materials, there is thedisadvantage that, after the division using conventional tools, a partof the molding material which has been separated off frequently remainsadhering to the remainder of the molding material, having an extremelyadverse effect on the product quality or even making the productsunusable.

The risk of contamination of molding materials by abraded materials anddischarges of the gradually wearing tools may be mentioned as a furtherdisadvantage, which occurs in particular in the case of moldingmaterials which contain sensitive components. In such a case, aninvestigation of the products must follow in order to counteract therisk of further processing contaminated molding materials or bringingthem onto the market. Choosing only completely safe tools is analternative, which may entail considerable research activities andcapital costs.

It is an object of the present invention to remedy these disadvantagesoccurring in conventional processes.

We have found that this object is achieved by a process for the divisionof a pasty molding material, wherein, for the division, the pastymolding material is brought into contact with at least one streamcontaining at least one fluid medium.

The term “division” as used in the context of the present inventionincludes, on the one hand, procedures in which a part is completelyseparated off from the molding material by bringing the pasty moldingmaterial into contact with the stream containing the at least one fluidmedium. The cutting to length of a strand of a molding material may bementioned as an example of this complete separation. The term “division”also includes procedures in which said stream is brought into contactwith the molding material in such a way that the molding material is notcompletely divided. In the latter embodiment, for example, an incisioncan be made in a molding material strand by means of the stream, thedepth of the cut being chosen so that the molding material strandremains in the form of an integral piece.

The term “molding material” as used in the context of the presentinvention includes materials which are subjected to at least one shapingstep. This includes procedures in which the molding material is dividedaccording to the invention in the shaping step. Before the divisionaccording to the invention or after the division according to theinvention or both before and after the division according to theinvention, the pasty molding material can be subjected to at least onefurther shaping step.

Thus, as further shaping steps, it is possible to provide, for example,one or more further division steps which are carried out eitheraccording to the invention by means of a stream containing at least onefluid medium or by conventional methods of the prior art, for example bymeans of a mechanical division.

Shaping processes differing from division processes are also possible asfurther shaping steps. For example, a strand of a molding material canbe modified by shaping in such a way that, for example, its lengthand/or its diameter and/or its cross section is changed. It is alsopossible, for example, for a piece of a molding material, for example ofa molding material strand, which has been separated off and results froma novel division process to be modified in at least one of itsgeometrical properties, for example by kneading, rolling, compaction,drawing or other processes. The molding material or the piece of amolding material which results from the novel division process can besubjected to shaping effects also by, for example, one or more dryingand/or heating processes or by one or more chemical processes.

A procedure in which, in the division step, the bringing of a pastymolding material into contact with a stream containing at least onefluid medium is combined in a suitable manner with one or moreconventional division processes according to the prior art may also bementioned as a possible embodiment of the novel process. Thus, it isconceivable inter alia that, as described above, by means of the novelprocess, for example a pasty molding material strand is provided withone or more incisions while retaining its integral nature and at leastone of these incisions is completely cut through by one or moreconventional tools. A converse procedure in which the pasty moldingmaterial strand is provided with at least one incision by means of oneor more conventional tools while retaining its integral nature and atleast one of these incisions is completely cut through by means of thenovel process is also possible.

In the context of the present invention, the term “fluid medium” isunderstood as meaning all states of material which are between ideal gasand solid under the conditions prevailing during the division.Accordingly, the term fluid medium covers, for example, dense gases,liquids, melts or supercritical phases. In the context of the presentinvention, finely divided solids in one or more gases or liquids, forexample fluidized beds or magnetic liquids, also constitute fluid media.In the novel process, gases or liquids are preferably used as fluidmedia.

Accordingly, the present invention also relates to a process, asdescribed above, wherein the fluid medium is a gas or a liquid.

For the purposes of the present invention, two or more different fluidmedia may also be used. In this respect, for example, the stream whichis used for division of the pasty molding material may contain two ormore different fluid media, for example two or more different gases ortwo or more different liquids or at least one gas and at least oneliquid being conceivable.

In a further embodiment of the novel process, two or more streamscontaining at least one fluid medium are used for the division of thepasty molding material.

This embodiment in which two or more streams are used includes, interalia, those procedures which employ two or more streams, at least two ofwhich differ in their composition. Different compositions can beachieved, inter alia, if at least two of the streams contain differentfluid media. Different compositions can furthermore be achieved if thestreams contain the same fluid media but the concentrations in theindividual streams differ with respect to the fluid media or the streamsdiffer in further components other than the fluid media.

In a particularly preferred embodiment of the novel process, the streamwhich is brought into contact with the pasty molding material consistsof the at least one fluid medium.

Regarding the bringing of the stream containing at least one fluidmedium into contact with the pasty molding material, all suitableprocedures are possible.

In a preferred embodiment, the stream is brought, under a certainpressure, at a certain volume flow rate and a certain temperature of thestream, in a certain direction and with a certain cross-sectional areaand geometry, continuously into contact with the molding material undercertain ambient conditions. In this context, the term continuous isunderstood as meaning all procedures in which, in the course of a singledivision process, the molding material is permanently in contact withthe stream containing at least one fluid medium.

This embodiment of bringing into contact continuously includes, interalia, those procedures in which the stream is fed with constantpressure, constant temperature, constant volume per unit time, constantdirection and constant cross-sectional area and geometry to the molding.This embodiment in turn includes, inter alia, those procedures in whichsaid parameters of the stream containing at least one fluid medium areconstant at the outlet apparatus via which the stream is fed to themolding material, as well as procedures in which these parameters areconstant at the respective surface of the molding material. Regardingthe last two embodiments, it is accordingly conceivable for the outletorifice via which the stream is fed to the molding material to remain ina constant position relative to the molding material. Here, theparameters of the stream at the surface of the molding material and ofthe outlet orifice are constant. It is also possible for the position ofthe outlet orifice of the stream to change relative to the moldingmaterial in the course of the division process, with the result that thestream parameters at the surface of the molding material can be changedwith constant stream parameters at the outlet orifice and, in the caseof variable stream parameters of the outlet orifice, the streamparameters at the surface of the molding material can be kept constant.

The stream may also be fed batchwise to the molding material. Thisembodiment includes, inter alia, those procedures in which the pastymolding material is permanently in contact with the stream containing atleast one fluid medium in the course of a single division process, whileat least one of the variable parameters of this stream which aredescribed above is changed in the course of time. Thus, it isconceivable, for example, for the pressure at which the stream isdischarged or the pressure at which the stream strikes the pasty moldingmaterial to change in the course of this single division process. Thesame applies to the parameters described above, such as volume flowrate, temperature of the stream, cross-sectional area and geometry anddirection. Of course, the composition of the stream may also be changedin the course of time.

Apparatuses comprising the above-mentioned outlet orifice are, forexample, nozzles. Nozzles preferred among others in the novel processare, for example, fan-jet nozzles, which may be distinguished, forexample, by uniform liquid and pressure distribution of the dischargedstream, it also being possible to use those nozzles which have aspecific distribution of the fluid medium in the discharged stream.Examples of such distributions are, inter alia, parabolic or trapezoidaldistributions. For example, low-pressure or high-pressure nozzles verygenerally can be used as liquid or air nozzles or as both liquid and airnozzles. Depending on the fluid medium and/or the process conditions, itis possible to use nozzles which consist of materials such as metals,e.g. brass, acid-resistant steel, heat-resistant steel or titanium,plastics, such as polyvinyl chloride (PVC), polypropylene (PP) orHastelloy, or two or more of these materials. Nozzles of the typedescribed above are commercially available, for example from Lechler orSchlick.

In the context of the present invention, the term “a single additionprocess” is understood as meaning procedures in which part of a pastymolding material is completely separated off from the remainder of themolding material or, for example, an incision is made in the moldingmaterial while retaining the integral nature of the molding material.

In a preferred embodiment of the present invention, a strand of a pastymolding material is periodically cut to length. For example, the strandof the molding material can be moved at a constant feed speed past oneor more stationary outlet apparatuses through which one or more streamscontaining at least one fluid medium are discharged and brought intocontact with the strand. The length of the pieces which are separatedoff from the strand can be regulated by means of the frequency withwhich the stream is discharged. Thus, it is conceivable, inter alia, forthis pulse frequency also to be kept constant at constant feed speed ofthe strand with the result that, for example, strand pieces of equallength are obtained. It is also possible to change the pulse frequencyas a function of time at constant feed speed, with the result thatstrand pieces of defined different length are obtained. It is alsopossible to change the feed speed continuously or discontinuously as afunction of time and to keep the pulse frequency constant or to changeit continuously or discontinuously as a function of time. It is alsoconceivable for the at least one outlet orifice for the streamcontaining at least one fluid medium to be nonstationary. Here, the atleast one outlet orifice can be mounted, for example, on at least onedisplaceably arranged arm which moves parallel to the extrudate ofmolding material or in directions deviating therefrom. For each streambrought into contact with the molding material during a pulse, thecontinuous and discontinuous procedures described above with regard tothe application of the stream to the molding material are conceivable.

Accordingly, the present invention also relates to a process, asdescribed above, wherein a strand of a pasty molding material isperiodically divided.

Procedures in which a plurality of strands is simultaneously cut tolength are of course also conceivable. For example, such a plurality ofstrands is particularly preferably formed in an extrusion apparatus.

In a particularly preferred embodiment of the present invention, inwhich, for example, a continuous strand of a pasty molding material iscompletely separated off by the stream containing at least one fluidmedium, with the result that the continuous strand is cut to length,there is a considerable advantage which the novel process has over theconventional mechanical division tools, for example wires for cutting tolength. By using the fluid medium, the pulse frequency with which thestream is brought into contact with the molding material can becontrolled in a substantially more reproducible manner than was the caseto date. Consequently, the length of the strand pieces separated offfrom the molding material strand can also be adjusted in a morereproducible manner, from which applications in which a very homogeneousplurality of strand pieces is required benefit in particular. If, forexample, a pasty molding material is divided in order to produce bulkmaterial which is to be used with a high bulk density, the novel processis particularly advantageous since, in comparison with conventionalprocesses of the prior art, it reduces off-spec fragments or fines, orboth fragments and fines, by the superior division process.

Accordingly, the present invention also relates to the use of a fluidmedium for producing bulk material of high bulk density by periodicallyconstant division of a pasty molding material.

The present invention also relates to the bulk material itself, whichcan be produced by a process as described above, where catalyst moldingsmay be mentioned as particularly preferred bulk material in the contextof the present application.

In particularly preferred embodiments, the bulk density of the bulkmaterial which can be produced according to the invention is from 0.1 to10 g/cm³, more particularly preferably from 0.2 to 2 g/cm³, morepreferably from 0.3 to 1 g/cm³, and particularly preferably from 0.4 to1 g/cm³.

In principle, all conceivable pasty molding materials whose viscosity,with an appropriate choice of the properties of the stream containing atleast one fluid medium, and other process parameters, permits a divisionby the stream can be divided in the novel process. Examples of suchproperties of the stream are:

-   -   composition of the stream;    -   pressure at which the stream comes into contact with the molding        material;    -   temperature of the stream;    -   volume of the stream which is applied to the molding material        per unit time and unit cross section;    -   cross section of the contact surface between stream and molding        material;    -   geometry of the contact surface between stream and molding        material;    -   direction in which the stream strikes the molding material;    -   frequency with which the stream is applied to the molding        material;    -   distribution of the fluid medium in the stream.

In general, the pasty molding materials which can be processed in thenovel process are not subject to any further restrictions. The viscosityof the molding materials is in general from 300 to 5 000 N/cm²,preferably from 500 to 4 000 N/cm², particularly preferably from 1 000to 3 000 N/cm². Such pasty molding materials are obtained, for example,in the production or mass production of plastics products,pharmaceutical products, cleaning agents and personal hygienecompositions, food products, animal feeds or catalysts.

Viscosity data stated in the context of the present Application areunderstood as meaning values determined using a Zwick material tester ofthe type Z010/TN2S, equipped with the standard software testXpert. Themeasuring head (10 kN) originates from GTM, Gassmann & Theiss,Messgerätetechnik, with a test certificate from Zwick. The measuringapparatus has a measuring cylinder with a maximum capacity of 40 cm³ asthe lower part and a load cell (10 kN) with a ball attachment as theupper part.

In a very particularly preferred embodiment, the novel process is usedfor molding materials whose viscosity is from 1 000 to 3 000 N/cm².Pasty molding materials which have such viscosities are used, forexample, in the production of catalyst moldings.

In the context of the present invention, the term “catalyst molding” isunderstood as meaning moldings which serve as a prepared catalyst or asa catalyst precursor. Furthermore, catalyst moldings may have at leastone further component which does not have catalytic activity and, in thecase of a catalyst precursor, can be removed from the molding, forexample, in at least one further treatment step, for example in athermal treatment or a chemical reaction.

Examples of such catalysts are, inter alia, oxidation, hydrogenation,dehydrogenation, epoxidation, amination, alkylation, purification orreforming catalysts. Catalysts for removing oxides of nitrogen NO_(x) orfor decomposing N₂O may also be mentioned.

In an embodiment of the novel process which is preferred among others,epoxidation catalyst moldings are prepared, zeolite catalysts in turnbeing preferred as epoxidation catalysts. There are no particularrestrictions with regard to the zeolite catalyst moldings which can beprepared in the present invention.

Zeolites are known to be crystalline aluminosilicates having orderedchannel and cage structures which possess micropores which arepreferably smaller than about 0.9 nm. The network of such zeolites iscomposed of SiO₄ and AlO₄ tetrahedra which are linked via common oxygenbridges. An overview of the known structures is to be found, forexample, in W. M. Meier, D. H. Olson and Ch. Baerlocher, Atlas ofZeolite Structure Types, Elsevier, 4th Edition, London, 1996. Zeoliteswhich contain no aluminum and in which titanium in the form of Ti(IV) ispresent instead of some of the Si(IV) in the silicate lattice are nowalso known. These titanium zeolites, in particular those having acrystal structure of the MFI type, and possibilities for theirpreparation, are described, for example in EP-A 0 311 983 or EP-A 405978. In addition to silicon and titanium, such materials may alsocontain additional elements, for example aluminum, zirconium, tin, iron,cobalt, nickel, gallium, boron or small amounts of fluorine. In thezeolite catalysts preferably regenerated using the novel process, someor all of the titanium of the zeolite can be replaced by vanadium,zirconium, chromium or niobium or a mixture of two or more thereof. Themolar ratio of titanium and/or vanadium, zirconium, chromium or niobiumto the sum of silicon and titanium and/or of vanadium and/or zirconiumand/or chromium and/or niobium is as a rule from 0.01:1 to 0.1:1.

Titanium zeolites, in particular those having a crystal structure of theMFI type, and possibilities for their preparation, are described, forexample, in WO 98/55228, WO 98/55229, WO 98/55430, EP-A-0 311 983 orEP-A-0 405 978, the scope of which in this respect is hereby fullyincorporated by reference in the context of the present Application.Titanium zeolites having the MFI structure are known to be capable ofbeing identified from a certain pattern in the determination of theirX-ray diffraction pictures and additionally from a skeletal vibrationband in the infrared range (IR) at about 960 cm⁻¹ and therefore differfrom alkali metal titanates or crystalline and amorphous TiO₂ phases.

These include specifically titanium-, germanium-, tellurium-, vanadium-,chromium-, niobium- and zirconium-containing zeolites having thepentasil zeolite structure, in particular the types assigned, by X-raydiffraction, to the ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO,AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ATN, ATO, ATS, ATT,ATV, AWO, AWW, BEA, BIK, BOG, BPH, BRE, CAN, CAS, CFI, CGF, CGS, CHA,CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EMT, EPI,ERI, ESV, EUO, FAU, FER, GIS, GME, GOO, HEU, IFR, ISV, ITE, JBW, KFI,LAU, LEV, LIO, LOS, LOV, LTA, LTL, LTN, MAZ, MEI, MEL, MEP, MER, MFI,MFS, MON, MOR, MSO, MTF, MTN, MTT, MTW, MWW, NAT, NES, NON, OFF, OSI,PAR, PAU, PHI, RHO, RON, RSN, RTE, RTH, RUT, SAO, SAT, SBE, SBS, SBT,SFF, SGT, SOD, STF, STI, STT, TER, THO, TON, TSC, VET, VFI, VNI, VSV,WIE, WEN, YUG or ZON structure and mixed structures comprising two ormore of the above-mentioned structures. Titanium-containing zeoliteshaving the structure of ITQ-4, SSZ-24, TTM-1, UTD-1, CIT-1 or CIT-5 arefurthermore conceivable for use in the novel process. Furthertitanium-containing zeolites which may be mentioned are those having thestructure of ZMS-48 or ZSM-12.

Moldings of Ti zeolite catalysts having the MFI, MEL or MFI/MEL mixedstructure are preferably used in the novel process. Specifically, theTi-containing zeolite catalysts, which are generally referred to asTSI-1, TS-2 or TS-3, and Ti zeolites having a framework structureisomorphous with β-zeolite may furthermore be mentioned as beingpreferred.

The present invention accordingly also relates to a process as describedabove, wherein the pasty molding material comprises a titanium zeolitecatalyst.

The novel process is particularly advantageous, inter alia, for theproduction of catalyst moldings which are to achieve a high bulkdensity, since, as stated above, the division of the pasty moldingmaterial by means of a jet containing at least one fluid medium givesbulk material having a higher bulk density in comparison withconventional mechanical processes.

Catalysts having a high bulk density are, for example, epoxidationcatalysts which are used in a process for the preparation of alkyleneoxides, for example propylene oxide. Particularly preferred epoxidationcatalysts are, for example, the above-mentioned zeolite catalysts,particularly preferably the titanium zeolite catalysts.

The bulk density of these epoxidation catalysts which for example arepreferred is, for example, particularly preferably from 0.4 to 1 g/cm³.

Accordingly, the present invention also describes a process, asdescribed above for preparing a bulk material, wherein the bulkmaterial, in particular catalyst moldings, has a bulk density of from0.1 to 10 g/cm³, more particularly preferably from 0.2 to 2 g/cm³, morepreferably from 0.3 to 1 g/cm³, and particularly preferably from 0.4 to1 g/cm³.

The present invention also describes the use of a novel apparatus forthe preparation of catalyst moldings having a bulk density of from 0.1to 10 g/cm³, more particularly preferably from 0.2 to 2 g/cm³, morepreferably from 0.3 to 1 g/cm³, and particularly preferably from 0.4 to1 g/cm³.

In the novel process, the parameters which define the stream and aredescribed above can be adapted to the parameters of the pasty moldingmaterial to be divided, for example

-   -   viscosity;    -   geometry;    -   feed speed (in the case of a moving molding material);    -   composition.

If the chemical composition of the pasty molding material permits, forexample, nitrogen can be used as the fluid medium. This has theadvantage that, in many production processes, nitrogen is alreadypresent on site in gas networks. A stream which consists of compressedair, which is likewise generally present on site in gas networks, isalso conceivable. However, other gases, including noble gases, are ofcourse also conceivable, it being possible for the stream to contain oneor more of the gases or to consist of this at least one gas.

If, in a particularly preferred embodiment of the novel process, forexample, catalyst moldings comprising at least one titanium zeolite areprepared by division of pasty molding materials, a stream which consistsof compressed air is preferred.

Accordingly, the present invention also relates to a process, asdescribed above, wherein the stream substantially comprises air.

The term “air” as used in the context of the present invention isunderstood as meaning a gas or a gas mixture which substantiallycomprises nitrogen, preferably having nitrogen contents greater than orequal to 78% by volume, and is substantially present as a fixedinstallation in any laboratory and any production plant operated on apilot or industrial scale. Depending on the source from which the airoriginates, its composition may vary within the limits familiar to aperson skilled in the art.

If, for example, catalyst moldings are prepared in the novel process, itis also conceivable to use a stream which comprises at least onereactive gas. For example, the surfaces formed by the division processcan be oxidized by reactive gases, for example oxygen, or reduced byhydrogen. By means of such division processes, division and chemicalreaction of the surfaces forming during the division are combined in thenovel process, which ensures a highly economical process.

Accordingly, the present invention also describes a process for thepreparation of chemically modified moldings from a pasty moldingmaterial, wherein the pasty molding material is divided and chemicallymodified by a stream containing at least one fluid medium, the at leastone fluid medium comprising at least one medium reactive with respect tothe pasty molding materials.

The present invention also describes the use of a stream containing atleast one fluid medium for the preparation of chemically modifiedmoldings from a pasty molding material, wherein the at least one fluidmedium comprises at least one medium reactive with respect to the pastymolding materials, and the pasty molding material is divided andchemically modified.

Of course, it is also possible for the novel stream used to contain oneor more gases, for example noble gases and/or other gases inert withrespect to the chemical composition of the molding material, in additionto the reactive gas.

In the context of this embodiment it is also possible chemically tomodify not only the surfaces which form during the division process butalso the other surfaces of the pasty molding material and hence of theresulting molding. This can be effected, for example, by dividing astrand of a pasty molding material by a stream containing the reactivefluid medium in a first step. In the further course, in which the pastymolding material is moved past at least one outlet apparatus via whichthe stream is applied to the molding material and/or the outletapparatus is moved past the molding material, the stream is furtherapplied to the molding material, but the pressure of the stream isreduced to such an extent that the stream comes into contact with themolding material and hence permits the chemical modification of thesurface, but division no longer takes place. After a certain time inwhich that part of the molding material which is to be separated has thepredetermined length, the pressure of the stream is then increased insuch a way that a division process takes place again.

Accordingly, the present invention also describes the use describedabove and the process described above, the pressure at which the streamis applied to the molding material being variable.

As described above, the pressure of the stream containing the at leastone fluid medium can be completely adapted to the requirementsdetermined by the pasty molding material and the type of divisionprocess, for example complete separation or making an incision in themolding material.

If the stream used is, for example, a gas or gas mixture, pressures offrom a few millibar to high pressures of up to 2 000 bar are suitable.The temperature of the gas stream may be, for example, from roomtemperature to 700° C.

If, for example, a catalyst molding, for example one of the catalystmoldings described above as being preferred, is produced in the courseof the present invention, a gas stream which preferably substantiallycomprises air, in general at pressures of from 1 to 325 bar, preferablyfrom 4 to 200 bar, particularly preferably from 10 to 100 bar, is used.The gas stream has a temperature which is generally in the range fromroom temperature to 200° C., preferably from room temperature to 100°C., particularly preferably from room temperature to 50° C.

Accordingly, the present invention also relates to a process, asdescribed above, wherein the stream is brought into contact with thepasty molding material at a pressure of from 1 to 325 bar and at atemperature of from room temperature to 200° C.

It is furthermore particularly preferable if the parameters of the gasstream are chosen so that the pasty molding material is divided but isnot completely broken up or deformed. The advantage of the novel processof conventional mechanical division apparatuses is once again displayedhere, since pressure, temperature, volume flow rate and all otherparameters of the gas stream can be optimally adapted to theconsistency, for example plasticity and brittleness, of the respectivepasty molding material.

If, for example, a liquid is preferably used as the stream, pressuresand temperatures which are chosen to be similar to those used in waterjet cutting are generally employed.

If one or more liquids are used as the fluid medium in the course ofpresent invention, it is possible to use all liquids whose viscosityenables the flow velocity required for the desired division step to beestablished. If permitted by the chemical nature of the pasty moldingmaterial, for example, water is particularly preferred as a fluid mediumsince it is installed on site in many production facilities. In general,when a liquid is used as the fluid medium, a procedure should be adoptedin which the temperature of the stream and pressure at which the streamis discharged from the respective outlet apparatus and brought intocontact with the pasty molding material are adapted to the boiling pointof the liquid at the corresponding pressure. In general, the procedureis effected at below the boiling point of the liquid at this pressure.

In a more preferable embodiment of the novel process, the fluid medium,particularly preferably the at least one liquid, is collected after thedivision step and recycled to the process. If necessary, the fluidmedium can be subjected to one or more suitable purification steps orworking-up steps before the recycling.

Very generally, the present invention also describes the use of at leastone of the fluid media described above in the production of at least oneproduct from at least one pasty molding materials, the at least onefluid medium having a shaping effect on at least one pasty moldingmaterial in at least one step of this at least one production process.

Accordingly, the present invention relates to the use of a fluid mediumfor shaping a pasty molding material.

As described above, a very particularly preferred novel area of use isthe division of a pasty molding material by means of at least one streamcontaining at least one fluid medium.

Accordingly, the present invention also describes the use of a fluidmedium, as described above, wherein the shaping comprises a division ofthe pasty molding material.

In particular, the present invention describes the use, as describedabove, wherein, as the pasty molding material, a molding material whichcontains at least one catalyst or at least one precursor of a catalystor at least one catalyst and at least one precursor of a catalyst issubjected to a shaping operation, the catalyst preferably being anepoxidation catalyst, more preferably a zeolite catalyst, moreparticularly preferably a titanium zeolite catalyst.

The present invention is illustrated in the following examples.

EXAMPLES Example 1 According to the Invention

In a kneader, 150 g titanium zeolite powder was mixed with 125 g silicasol Ludox AS 40, 120 g aqueous polystyrol dispersion (30% by weightpolystyrol), 6 g methylcellulose, 2 g polyethylene oxide and 48 gdemineralized water, and kneaded for 60 minutes. Subsequently, theresulting paste was shaped using a matrix having a diameter of bore of1.5 mm, and a mold pressure of from 80-100 bar.

At the working face of the matrix, 2 fan nozzles (Schlick company, name19828, mod. 650, mouth piece size 0, capacity 2.5 l/min at 3 bar, angleof dispersion 90°) were placed which were run with compressed air at 10bar. The outgoing air jet was pulsatorily controlled by an electrovalve.

The strand green products leaving the mold were cut wherein, bycombining the advance of the paste and the pulse frequency of the airjet, it was possible to adjust the length of the strands in the narrowrange of from 4-8 mm.

Finally the strand green products were dried at 120° C. overnight in airand calcined at 500° C. in air for 3 hours.

The catalyst thus produced had a bulk density of 440 g/liter.

Example 2 Comparative Example

In a kneader, 150 g titanium zeolite powder was mixed with 125 g silicasol Ludox AS 40, 120 g aqueous polystyrol dispersion (30% by weightpolystyrol), 6 g methylcellulose, 2 g polyethylene oxide and 48 gdemineralized water, and kneaded for 60 minutes. Subsequently, theresulting paste was shaped using a matrix having a diameter of bore of1.5 mm, and a mold pressure of from 80-100 bar.

At the working face of the matrix, a cutting tool consisting of a tensemetal wire was placed which periodically oscillated along the workingface. The cut off strand green products had a length of from 4-18 mmwith a broad length distribution. The strands were slightly curved andpartially glued together alongside.

Finally the strand green products were dried at 120° C. overnight in airand calcined at 500° C. in air for 3 hours.

The catalyst thus produced had a bulk density of only 308 g/liter.

1. A process for the division of a pasty molding material with aviscosity of from 300 to 5 000 N/cm², wherein, for the division, atleast one strand of the pasty molding material is brought into contactwith at least one stream containing at least one fluid medium, whereinthe stream substantially comprises at least one reactive medium, wherethe strand is periodically divided and wherein the length of the pieceswhich are separated off from the strand is regulated by means of thefrequency with which the stream is discharged and wherein said at leastone reactive medium is reactive with respect to the pasty mouldingmaterials.
 2. The process as claimed in claim 1, wherein the fluidmedium is a gas or a liquid.
 3. The process as claimed in claim 1,wherein the stream is brought into contact with the pasty moldingmaterial at a pressure of from 1 to 325 bar and at a temperature fromroom temperature to 200° C.
 4. The process as claimed in claim 1,wherein the pasty molding material comprises a titanium zeolitecatalyst.
 5. The process as claimed in claim 1, wherein a bulk materialwith a bulk density of from 0.1 to 10 g/cm³ is obtained.
 6. A processfor preparing a titanium zeolite catalyst molding with a bulk density offrom 0.1 to 10 g/cm³, wherein a strand of a pasty molding material witha viscosity of from 300 to 5 000 N/cm², comprising the titanium zeolitecatalyst, is periodically divided by a stream substantially comprisingat least one reactive medium at pressures from 4 to 200 bar, and whereinthe length of the pieces which are separated off from the strand isregulated by means of the frequency with which the stream is dischargedand wherein said at least one reactive medium is reactive with respectto the pasty moulding materials.
 7. A titanium zeolite catalyst moldingwith a bulk density of from 0.1 to 10 g/cm³, obtained by a processaccording to claim 6.